<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<style>
    *{padding: 0; margin: 0;}
    .cont{width: 800px; height: 300px; position: relative; font-size: 50px; display: flex;flex-direction: row; justify-content: center; align-items: center; margin: 500px auto; z-index: 0;}
    .cont::before{content:'';width: 800px; height: 300px; border-top: 25px dashed blue; border-right: 25px dashed blue; position: absolute; left: 0; top: 0;z-index: 1;}
    .cont::after{content:'';width: 800px; height: 300px;  border-left: 25px dashed blue; border-bottom: 25px dashed blue; position: absolute; left: 0; top: 0; z-index: -1;}
    .cont::before, .cont::after{transform: rotate(45deg); animation: road 10s infinite linear;}
    @keyframes road{
        to {
            transform: rotate(360deg);
        }
    }
</style>
<body>
    <div class="cont">旋转旋转旋转旋转旋转旋转旋转旋转旋转旋转旋转旋转旋转旋转旋转旋转旋转旋转</div>
</body>
</html>